With due respect, if you're in your late 40s and have been in the same job for "decades", then you don't have any personal experience with the hiring ageism com

With due respect, if you're in your late 40s and have been in the same job for "decades", then you don't have any personal experience with the hiring ageism common in our industry. And I totally agree with and live by the 3 points you made (except the 3rd, in some circumstances). But that's the problem with ageism. If you look like you're over 40, then it doesn't matter if you follow that advice or not, younger companies will often still hold your age against you.